Empty XML node and how to handle

Hello,

I have a XML file that has empty stock in some products, like this:

<stock/>

I have alredy written a PHP function in order to manage the stock of the products.. Thus, how to handle this <stock/> value? Nothing seems to be working.. For example, I have already wrote this:

function manage_stock($stock_qty) {
if(!isset($stock_qty) || $stock_qty === “” || empty($stock_qty) || is_null($stock_qty)) {
return 10;
}
}

But the IF statement does not seem to work! How to check the values of these XML elements? Thanks in advance